A cross-sectional study: analysis of anatomical variation in the right upper lung intersegmental vein V2a based on a 3D reconstruction technique.

Background: This study aimed to summarize and analyze the anatomical structures of the right upper lung intersegmental vein V2a based on 3-dimensional (3D) reconstruction technology. Methods: We collected the enhanced computed tomography (CT) scans of 157 patients with pulmonary diseases, and reconstructed the right upper lung tissue structure through interactive qualitative and quantitative analysis (IQQA). According to the reconstruction results, the V2a of the right upper pulmonary intersegmental vein was returned to different veins for classification, and the subtypes were further subdivided according to the different vascular routes and the location of the pulmonary segmental bronchus. Results: Among 157 patients, there were 4 types of V2a according to the anatomical position of the veins. In type B (15 cases, 9.6%), V2a returned to the apical vein V1. In type C (2 cases, 1.3%), V2a did not exist, while in type D (1 case, 0.6%), V2a directly flowed into the right atrium. Type A is further divided into three subtypes (A1, A2, A3) according to the type of veins returned and the anatomical location of their confluence. In subtype A1 (110/139 cases, 79.1%), V2a returned to the posterior segment central vein. In subtype A2 (8/139 cases, 5.8%), V2a flowed from the B2 mediastinal surface down to the interlobular part of the posterior segmental vein. In subtype A3 (21/139 cases, 15.1%), V2a flowed between B1a and B2a and back to the central vein at the junction of the B2 and B3 bronchus. Type B is further divided into 3 subtypes (B1, B2, B3) according to the location of the apical posterior segmental bronchus. In B1 subtype (1/15 cases, 6.7%), V2a continued from the mediastinal surface of B1 back down to V1. In B2 subtype (7/15 cases, 46.7%), V2a continued from the medial side of the B1 lung back down to V1. In subtype B3 (7/15 cases, 46.7%), V2a flowed back into the central part of the posterior segmental vein. Conclusions: This study, supported by 3D reconstruction technology, preliminarily summarized the V2a typology and further refined the anatomical differences of each subtype.